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EP-4210936-B1 - A PANEL PROFILE AND METHOD FOR MANUFACTURING THEREOF

EP4210936B1EP 4210936 B1EP4210936 B1EP 4210936B1EP-4210936-B1

Inventors

  • UOTILA, Tiina, Terhikki
  • LINDSTRÖM, Christoph, Gilbert
  • SJÖDAHL, Kim, Matias

Dates

Publication Date
20260506
Application Date
20210906

Claims (9)

  1. A cover panel of a radome with a signal window, wherein - the cover panel (40) has a pultruded sandwich structure with at least one a core layer (42) and surface layers (44) on both sides of the sandwich structure, the sandwich structure having a length (L) extending along the pultrusion direction of the sandwich structure and a width (W) perpendicular to the length (L), - the core layer (42) comprises at least one signal window section (46) made of a substantially radiofrequency, RF, transparent material, , - the core layer (42) further comprises a peripheral section surrounding the signal window section (46), the peripheral section comprising at least one reinforcing material and having a different material composition than the signal window section (46), characterized by - the peripheral section comprising first, lengthwise peripheral portions (48b) extending along the length (L) of the sandwich structure on both widthwise sides of the signal window section (46), and - the peripheral section further comprising second, widthwise peripheral portions (48a) extending along the width (W) of the sandwich structure on both lengthwise ends of the signal window section (46).
  2. A cover panel according to claim 1, wherein - the lengthwise peripheral portions comprise reinforcing structures made of continuous fibres extending in the lengthwise direction, - the widthwise peripheral portions comprise reinforcing structures made of discrete reinforcing elements.
  3. A cover panel according to claim 2, wherein the thickness of the signal window section is configured to correspond with a length of one or multiple quarters of an effective wavelength of an RF signal traveling through the signal window section, the RF signal being in a nominal signal frequency range of an antenna in the radome.
  4. A cover panel according to any one of claims 1 to 3, wherein the signal window section is made of one or more natural or synthetic cellular materials.
  5. A cover panel according to claim 4, wherein the fibres of the surface layers are in the form of woven fabric or layers thereof.
  6. A cover panel according to claim 5, wherein the thickness of the foam is 0.1 - 50mm and the thickness of the surface layers is 0.1 - 5 mm.
  7. A telecommunication antenna arrangement comprising an antenna and a radome protecting the antenna, wherein - the radome comprises a cover panel according to any one of claims 1 to 6, - the thickness of the signal window section of the cover panel corresponds with a length of one or multiple quarters of wavelength a RF signal traveling through the signal window section, the RF signal having a frequency in an nominal signal frequency range of the antenna.
  8. A pultrusion method for manufacturing a cover panel (40) of a telecommunication antenna radome with a signal window, the method comprising - providing a plurality of discrete core elements (22a, 22b) between two surface layers (44), - pulling the surface layers (44) and the core elements (22a, 22b) therebetween through a pultrusion process, thereby forming a continuous cover panel profile with a sandwich structure, the panel profile having a length (L) extending along the pultrusion direction of the panel profile and a width ( W ) perpendicular to the length ( L ), - cutting the continuous cover panel profile at predetermined lengths to form the cover panel, wherein - the discrete core elements (22a, 22b) comprise at least two different types of elements, the two different types including a first element and a second element, wherein - the first element (47) is made of a substantially radiofrequency, RF, transparent material, and - the second element (49a) is a reinforcing element that has a different material composition than the first element, and - the core elements are arranged to a sequence so that the manufactured panel profile has a signal window in the form of at least one first element (47) surrounded by reinforcing elements from each side, characterized in that - the second elements (49a) form widthwise reinforcing elements extending along the width of the panel profile, the widthwise reinforcing elements being positioned at both lengthwise ends of the signal window, and - continuous fibres (49b) extend along the length of the panel profile, the continuous fibres being positioned on both widthwise sides of the first and second elements.
  9. A method according to claim 8, wherein the method comprises - mounting the core elements on a continuous carrier in the order of the sequence, and - supplying the core elements to the pultrusion process on the carrier.

Description

FIELD The invention relates to pultruded panel profiles, and particularly to pultruded panel profiles with sandwich structure. BACKGROUND INFORMATION Pultrusion is a continuous process for manufacture of composite materials with uniform cross-section. In a pultrusion process, continuous fibres wetted in a resin are pulled through a heated mould. As the resin-wetted fibres are pulled through the heated mould, the heat causes the resin to harden, and thus, a continuous profile is formed. The shape of the mould defines the cross-sectional shape of the profile. In some applications, an additional core material may be supplied to the mould together with to the fibres. In this manner, more versatility can be introduced to functional characteristics of pultruded profiles. However, the introduction of a core material into a pultruded profile may significantly lower the mechanical characteristics of the profile. Further, depending on the price of the core material, the manufacturing costs may increase significantly. US patent publication US 9,764,520 B2 describes a 3D thermoplastic composite pultrusion system and method. BRIEF DISCLOSURE An object of the present disclosure is to provide a panel profile and a method for manufacturing thereof so as to alleviate the above disadvantages. The object of the disclosure is achieved by a panel profile and a method which are characterised by what is stated in the independent claims. The preferred embodiments of the disclosure are disclosed in the dependent claims. The present disclosure describes a method for manufacturing a pultruded panel profile. The method produces a panel profile with a sandwich structure that has core layer in the middle. The core layer is made of discrete core elements of a plurality of different types. The different types of core elements act as functional inserts in the composite. With the method according to the present disclosure, localized functionalities (such as a distinct signal window) can be formed in a predetermined position in a composite structure of the panel profile. At the same time, the continuous nature of the pultrusion process can be maintained. BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which Figure 1 shows an example of a pultrusion process.Figure 2 shows a simplified example of a continuous panel profile according to the present disclosure.Figures 3a to 3c show exemplary arrangements of core elements according to the present disclosure; andFigure 4a and 4b show a cover panel with a signal window according to the present disclosure. DETAILED DISCLOSURE The present disclosure describes a pultrusion method for manufacturing a continuous panel profile. In a pultrusion process, continuous fibres wetted in a resin are pulled through a heated mould. As the resin-wetted fibres are pulled through the heated mould, the heat causes the resin to harden, and thus, a continuous profile is formed. In the context of the present disclosure, the term "continuous profile" refers to a structure that continuously has the same exterior shape for its cross section throughout its length. However, the internal structure of the cross section may change along the length of the panel. The term "length" refers to the dimension of the panel profile extending in the direction of the pulling direction of the pultrusion process. Dimensions "width" and "thickness" are perpendicular to the length. The shape of the mould defines the shape of the cross section of the profile in the pultrusion process. Figure 1 shows an exemplary embodiment of a pultrusion process. In Figure 1, fibres 8 are pulled from reels 18 to be wetted in matrix resin 19. Resin-wetted fibres 8' are pulled into a heated mould 15. A core material 9 is pulled in the mould 15 together with the fibres 8'. In Figure 1, the core material 9 is guided from a reel 12. The fibres 8, 8' are guided only into surface layers of profile walls and the core material 9 is guided between the surface layers. Before entering the mould, the resin-wetted fibres 8' may pass through preforming guides 10 and a forming die 7 in order to guide the fibres to a desired configuration. The wetted fibres 8' and the core material 9 may also pass through a forming die 7 prior to the mould 15 in order to finalise the cross-sectional shape of the panel. As the fibres 8' and the core material 9 are pulled through the mould 15, a profile 17 is formed. As shown in Figure 1, the profile has a core 16. The pulling is performed by the means of a pulling device 14. Finally, the pultruded continuous straight profile 17 may be chopped up at desired lengths by a cutting saw 13. In the method according to the present disclosure, the core material comprises discrete core elements. The core material may be made of discrete core elements alone or the core material may be made of discrete core elements and other,